A. Field of the Invention
The present invention relates to computer memory devices and, more specifically, to mechanisms for accessing a drive controller's full instruction set when it is attached to a tailgate device.
B. Description of Related Art
There are many situations where it is desirable for a host computer to read data from a long-term memory storage device, such as a hard drive. There are a number of different drive interfaces, such as USB, IDE and FireWire, among others. There are occasions when the host does not have a matching interface for the device to be read. In this case, a tailgate device is used. A tailgate device is a device with two different interfaces, such as USB and IDE. FIG. 1 is a diagram illustrating a tailgate device in use. Host 105 is connected to Tailgate 100 through interface 110. Tailgate device 100 is connected to storage device 120 through interface 115. Interface 110 and interface 115 may be of different types.
Different interfaces have different command sets. For example the USB command set does not support the IDE Host Protected Area (HPA) command set. Therefore, if interface 110 is USB and interface 115 is IDE, there is no way known in the art for host 105 to issue an HPA command to storage device 120. If the host cannot issue HPA commands then the host may not have full access to the storage device. There is an obvious benefit for a host using a tailgate device to have access to hidden or protected areas on a storage device.
In addition to different interfaces having different command sets, they also treat drives differently. The last few sectors of an IDE drive may not be able to be read under Microsoft Windows if the drive is connected to a USB tailgate device. Further, Windows may not even know that it does not have access to all of the sectors on the drive. There is an obvious benefit for a host using a tailgate device to have access to all sectors on a storage device.
The above discussion has focused on IDE and USB interfaces, but our invention is not limited to these. One skilled in the art will appreciate that other drive types such as SCSI and FireWire have similar concerns.
Accordingly, there is a need in the art for an improved mechanism to enable a tailgate device to have full access to a long-term storage device.